Research into the effects of uncontrolled moisture, including moisture in the form of high humidity levels has clearly demonstrated that exposure to high humidity levels leads to a variety of building related problems. Relevant background material on moisture effects and control is included in the references identified in and incorporated by reference into this disclosure. The extent of the resulting damage will be related to many factors, however as a general principle, increasing amounts of moisture distributed in expanding areas for increasing amounts of time will all (individually and in combination) result in a corresponding increase in the negative impacts on the building. There is a very clear relationship between moisture management problems and mold contamination problems in buildings.
The range of negative impacts is large, however some examples include:
1. Cosmetic and structural damage caused by staining, corrosion, dimensional changes due to moisture content changes in materials and microbial growth such as fungi, including mold and wood decaying fungi.
2. Damage to other building systems such as corrosion of electrical components and mold growth on duct and pipe insulation.
3. Increased building operating costs due to excessive moisture removal loads on cooling or dehumidification equipment, make-up air systems or other building services.
4. Loss of use of buildings or areas of buildings. In the case of homes, schools, health care facilities and other buildings, the loss of use may have significant impacts on many aspects of the occupants and the ability to provide for basic needs.
5. Increased custodial and maintenance requirements to maintain and remediate the effects of moisture problems.
6. Reduction in the value of the building as an asset due to the inherent liabilities associated with moisture and/or mold problems.
7. A diverse range of adverse health affects have been attributed to the exposure of occupants to damp and/or moldy buildings.
These basic concepts and concerns form the focal point of many documents related to investigating moisture management problems in buildings, preventing moisture damage and remediating moisture damage.
Various organizations, including Canadian and United States Federal Government Agencies, have recognized moisture management and mold contamination problems as being significant issues for buildings and building occupants. Regular inspections and prompt responses to problems are a key component of good building management. References related to the general issues of building science, indoor air quality, moisture management and mold related building issues include (the disclosures of which are incorporated herein by reference):
(1) “Mold Remediation in Schools and Commercial Buildings”, US EPA, Washington, D.C., March 2001.
(2) “Health Canada proposes a new guideline on mould in residential indoor air”, Environmental and Workplace Health, Health Canada, Ottawa, ON., Jan. 26, 2007.
(3) “Fungal Contamination in Public Buildings: Health Effects and Investigation Methods”, Health Canada, Ottawa, ON., 2004.
(4) “Clean-Up Procedures for Mold in Houses”, Canada Mortgage and Housing Corporation, Ottawa, ON., Revised 2005.
In the specific area of moisture problems in building crawl space foundations, the following reference paper contains material that can serve as background and supporting information, and this paper is incorporated herein by reference:
Figley, D. A., Sieber, R. “Cleanup of Microbial Contamination in Major Building Crawlspaces”, Proceedings of the 9th International Conference on Indoor Air Quality and Climate, Indoor 2002, Monterey, Calif., Jun. 30-Jul. 5, 2002.
This paper summarizes the experiences obtained from the investigation and remediation of a number of building crawl spaces and identifies the significant problems caused by the lack of moisture control and early detection of major moisture release events. The material and concepts described in this paper form part of this disclosure and are included by reference.
Moisture management is the general art and process of understanding and controlling moisture activity in a building structure. Moisture can be present in many forms including, but not limited to:
(1) vapor or humidity in the air;
(2) water evaporated, absorbed or precipitated through dew or condensation, typically onto surfaces or into structural or building assemblies and volumes including moisture present on or within building components including structural members;
water present as snow, ice, or frost buildup which can melt to produce an uncontrolled source of liquid water; or
(3) water present as an exposed liquid, typically as puddles or that might lie on surfaces as it migrates to a lower level, such as wetted walls, foundations or window surfaces.
Mechanisms that may bring water within a building (or alternately, collect small amounts of water until they form a large source of moisture) are many, including but not limited to:
(1) humidity present in the ventilation air source, typically outdoor air that is drawn into the building and conditioned either intentionally as part of the HVAC makeup air or combustion air or unintentionally as a result of leaks within the building envelope air/vapour barrier assembly;
(2) water introduced by introducing wet articles into the conditioned building envelope such as wet clothing, snow and rain on articles of equipment, vehicles and the like, drying of wet materials such as firewood, etc.;
(3) humidity introduced by occupant activities such as cleaning, washing, clothes drying, cooking, plant watering and bathing;
(4) moisture introduced through unintentional water releases such as plumbing and heating system leaks, sewer backup, vandalism and the like;
(5) moisture introduced through structural or moisture barrier leaks including but not limited to roof and foundation leaks, absent or impaired access hatches or windows or the like that can allow, rain, snow melt, surface or ground water to enter the conditioned spaces of a building; or
frost or ice buildup on cold surfaces exposed to moist air which at some point may thaw and produce unanticipated water sources.
Note, that within this disclosure, “conditioned” refers to air, air volumes and building zones intended to be brought into and maintained within a define or acceptable range of temperatures through the use of HVAC techniques known to the art.
Current best practices for moisture control can include a combination of:
(1) proper building and building envelope design, including material selection
and construction methods;
(2) foundation drainage systems including collection and disposal piping systems;
effective environmental water drainage including building location selection, grading the building surroundings for proper surface runoff of storm water drainage and snow melt, effective snow removal practices and the like;
(3) well conditioned air to ventilate the affected building volumes;
training for occupants and building operators to make them aware of their impact on moisture management and to provide them with practices and policies to reduce moisture problems in buildings;
(4) routine inspection and maintenance of all building areas and systems to allow for detection and repair of moisture management problems; and
(5) detection of water leakage and/or water collection in both occupied and unoccupied areas using sump alarms, floor wetting detectors, water conductivity alarms and the like.
However, in real world practice, it is not always possible to incorporate or design for all possible scenarios or extremes, nor for the occurrence of the myriad possible building system impairments or breakdowns. As well, traditional sump pump alarms and floor wetting detectors can not always detect a leak or water entry point, since for these to function properly, significant amounts of water need to be present at the detection site. Excessive moisture can occur without these systems being activated. Confounding this situation is the effect of occupant lifestyle and in many cases, the lack of continued effective, routine inspections and maintenance.
It should also be noted that many locations in a typical building structure are not easily inspected on a day-to-day basis, so these locations tend to be investigated only when problems show up elsewhere in a building or there are other reasons to suspect a problem condition might be present.
For instance, conditioned crawlspaces under large buildings are difficult to inspect fully, as access is restricted, lighting is typically poor and there are often regions that have poor sight lines from where an inspector can position themselves. Additionally, these crawlspaces are often subdivided into relatively small areas as part of the fire protection and containment design of a building. The crawlspaces are often also where many of the buildings service lines run, such as water and sewer lines which can leak and are also where water from leaks and spills on higher floors migrates.
As a net result, these types of spaces can often have significant moisture problems for extended periods before being discovered. These types of situations are common in unsupervised areas in many buildings structures such as nursing residences, schools, homes residences, public buildings, offices and other such structures. These problems can also be present in occupied portions of buildings if the occupants are not observant or are not trained to recognize conditions indicative of moisture control failures.
Of further concern are buildings or building areas that may not normally be occupied, may not be frequently inspected or may otherwise be out of sight or out of mind for extended periods. These scenarios occur often, for instance with:
(1) buildings not occupied for periods of a day or more, such as churches, meeting halls, homes with vacationing occupants or for sale, business offices that are empty over the weekend and the like;
(2) schools closed for the season or for holidays;
(3) buildings with seasonal occupancy such as cabins, camps and the like; and
(4) buildings not intended to be regularly occupied such as pump houses, utility buildings, storage sheds and warehouses, parking garages and the like.
As a result, many buildings suffer serious damage from moisture control problems that could otherwise be avoided given an appropriate measurement and warning system capable of detecting the moisture problems early.